‘HBC 638’ is a product of a controlled breeding program carried out by the inventors in the Yakima Valley of Washington State. ‘HBC 638’ was one of several seedlings resulting from a controlled cross made in 2008 with female parent ‘HBC 366’ (a patented variety under U.S. Plant Pat. No. 25,899), and male parent ‘21-10-21’. Seedling plants from this cross were planted in 2009 and screened for disease resistance and sex in a greenhouse and field nursery near Granger, Wash. A single plant of ‘HBC 638’ was selected in 2011. In 2012 ‘HBC 638’ was asexually reproduced via softwood cuttings, and expanded to 14 plants in an evaluation block near Toppenish, Wash. In 2014 ‘HBC 638’ was further expanded to a 1 acre test block near Toppenish, Wash. with plants asexually reproduced via softwood cuttings. The ‘HBC 638’ plants have now been observed and evaluated for several years. Throughout several generations of asexual propagation, ‘HBC 638’ has been observed to retain its distinctive characteristics and remain true to type.